N-terminal palmitoylation of PSD-95 regulates association with cell membranes and interaction with K+ channel Kv1.4.
Ion channels and associated signal transduction cascades are clustered at excitatory synapses by PSD-95 and related PDZ-containing proteins. Mechanisms that target PSD-95 to synaptic membranes, however, are unknown. Here, PSD-95 is shown to partition as an integral membrane protein in brain homogenates. Metabolic labeling of brain slices or cultured cells demonstrates that PSD-95 is modified by thioester-linked palmitate, a long chain fatty acid that targets proteins to cell membranes. In fact, PSD-95 is a major palmitoylated protein in intact cells, and palmitoylated PSD-95 partitions exclusively with cell membranes. Mutagenesis indicates that palmitoylation of PSD-95 occurs on conserved N-terminal cysteines 3 and 5. Palmitoylation-deficient mutants of PSD-95 do not partition as integral membrane proteins and do not participate in PDZ-ion channel interactions in vivo. This work identifies palmitoylation as a critical regulatory mechanism for receptor interactions with PSD-95.
Topinka
J R
JR
Department of Physiology, University of California at San Francisco, 94143, USA.
Bredt
D S
DS
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D019556:COS Cells / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D051665:Kv1.4 Potassium Channel; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats
D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; C496979:Kcna4 protein, rat; D051665:Kv1.4 Potassium Channel; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C033652:postsynaptic density proteins; D019308:Palmitic Acid